Diabetes mellitus is a disorder in which the body does not produce enough or respond normally to insulin, causing blood sugar (glucose) levels to be abnormally high. The aim of the study was to assess the effectiveness of Andrographis paniculata leaf and stem bark extracts in management of Alloxan induced diabetes Wistar rats. Fifty (50) Wistar rats were divided into eight groups, namely; group A (normal control), B, C, D, E, F, G and H (treatment groups). The study was conducted for four (4) weeks by measuring blood glucose levels in first four weeks. The result showed that the diabetic rats administered with 500mg/kg of aqueous leaf extract and 250mg/kg of stem bark extract were significantly lower than those of untreated control groups. However, the combined dose of 250mg/kg aqueous leaf and 250mg/kg stem extracts were not significantly different from untreated control group. Findings of the study have demonstrated that leaves and stem extract of A. paniculata exhibited significant blood sugar lowering property in Alloxan induced diabetic Wistar rats. Keywords: Andrographis paniculata; Blood sugar; Diabetes mellitus; Wistar rat